Crank shaft



March 14, 1933. A. LACK 1,901,175

CRANK SHAFT Filed April 1, 1931 I 1 A 7 1 A Patented Mar. 14, 1933 tnor n nae-x, or snrior'r, sconsin; assrenoa i a rrnrnors 'ro n snooker, on criroieeo,

cRAu-K SHAFT Application filed April 1',

My invention relates to improvements in crank shafts especially adapted for use with rotary engines and has for one objectto provide a new and improved type of hollow,

' light,ecounterbalanced crank shaft andalso side Figure 5 is an end elevation with the crank shaft shown in Figure 3 seen from the right hand side;

Figure 6 is a detail section along the line 6-6 of Figure 4.

Like parts are indicated by like characters throughout the specification and drawing.

A is the short section, A the long section of a two part welded crank shaft. The short section A has at one end a cylindrical pocket A the pocket being bounded at one end by the solid end of the crank shaft, at the other end by an inwardly extending flange A whose internal diameter is less than the internal diameter of the pocket A. .As will hereinafter appear, the main bearing surface on the crank shaft is formed about the short section. A is a cylindrical pocket in the long section of the crank shaft, the internal diameter of which is the same as the internal diameter of the pocket A Extending toward the end of the crank shaft is a tubular passage or aperture A of lesser diameterthan the pockets A and A The end of the crank shaft surrounding the tubular passage A is reduced in diameter as at A to provide a male member of substantially the same outside diameter as the inside diameter of the flange A and the length of this male memher is substantially equal to the width of the 1931, Serial no 526,838.

flange ,A The ends of the members and A in opposition as indicated in Figure l are tapered asindicated at A so that when the male member penetrates thefemale mem her as indicated in Figure 2, there is an annular space provided which maybe filled by welding material as indicated at A when the two parts are welded together, the welding together of the two parts as indicated in Figure 2 providing the crank shaft blank upon which subsequent machine work be done.

Referring now to Figure3, it will beunderstood that the solid mass of material at each end of the crank shaft, beyond the pockets A? and A is, after the. shaft has been welded I together, turned down to provide crank pins B and E at opposed ends of the shaft. These tWQ Pins are identical except for. their posi:. tion with respect to the shaft andeach pin is S n y ta n 9 t ut r periphery f theerank shaft, and the diameter. f h

pin is just a littlejless than the radius of the crank shaft the two pinsare angulary spaced-? as indicated. Each pin is centrally apertured as B the outer portion of said '7 aperture being internally threaded as at B to-permit the attachment of the cover plate to hold connecting rod on the crank pin. A

drilled passage B extends inwardly from each pocket B to the hollow inside ofithe 89 crank shaft. The central portion of the crank shaft betweenthe weld and thepocket At is cut thereon an integral pinion B, the pinion I teeth being bounded at each end by grooves B Thatpart of the face of th'ecrank shaft 3 which is in line with the weld A? is peripherally channelled asat B so that the .weld with different mechanical or chemical characteristics resulting from the welding ac tion will not come in contact with the bearing 90,

support in which the crank shaft may be mounted for rotation. e V f f The hollow crank shaft is counter-balanced with respect to the eccentric or asymmetri 1 cal weight of the crankpin at either end by means of counterbalance weights C and (3?, These counter-balance weights are held in the pockets A and A respectivelyby means of screws C which penetrate the ends of the crankshaft and engage thecounterbal the passage B or through passages C and (l in that part'of the crank shaft'which does 7 not come in contact with any working part.

When this molten metal is introduced, the crank shaft is heldin proper position such that the path of molten metal will find its;

level in the correct place in the hollow crank shaft and will there solidify surrounding .the

holding screws and locking itself properly in position.

The process involved, namely, first forming the two separate apertured or pocketed crank shaft segments, then interlocking them and welding them together, then machining the outside of the hollow closed end-tube thus formed to proper size and shape and then introducing the plastic molten metal counterebalanced weights after the crank has I 7 been finished, makes it possible to produce a i as ' crank shaft of maximum strength and minimum weight and also makes it possible touse material such as nitro alloy and the like which can be easily and conveniently handled,

the job has been completed without danger of warping or changing to an unsatisfactory extent, size or shape of the various elements.

I claim: g

i .1. A crank shaft comprising an elongated hollow cylindrical member closed at both ends, crank pins projecting longitudinally from each closed end and parallel with the longitudinal axis of the shaft, a gear ,on the crank, shaft, the crank shafthaving cylindri cal'bearing surfaces at each side of the gear and'between it and the crank pins,the outside diameters of thegear and both bearing 7. surfacesbeing substantially the same, the-inside diameter of the hollow portion of the' shaft being greater at each end-adjacent the bearing. surfaces than it is centrally adjacent the gear, counterbalance weights of different material than the crank shaft contained within the hollow interior. of the shaft, one associated with each crank pin.

A crank shaft comprising an elongated hollow cylindrical member closed at both' ends, crank pins projecting longitudinally from each closed end and'parallel with the longitudinal axis ofthe shaft, a gear integral with the crank shaft, the crank shaft having cylindrical bearing surfaces, the outside diameters of the gear andboth bearing surfaces being substantially the same, the inside diameter of the hollow portion of the. shaft 7 being greater at each end'adjacent the bearing surfaces than it is centrally adj acentthe 5 gear, counterbalanceweights of different material than the crankshaft contained within the hollow interior of the shaft, one assopart of the hollow portion of the crank shaft oflarge diameter.

3. A crank shaft comprising an elongated hollow cylindrical member closed at both ends, crank pins projecting longitudinally from each closed end and parallel with the longitudinal axis of the shaft, a gear on the crank shaft, the crank shaft having cylindrical bearing surfaces at each'side of the gear, the outside diameters of the gear and both bearing'surfaces being substantially the same. 7

4. A crank shaft comprising an elongated hollow cylindrical member closed at both ends, crank pins projecting longitudinally from each closed end and parallel with the longitudinal axis of the shaft, 2. gear integral with the crank shaft, the crank shaft having cylindrical bearing surfaces at each side of the1 ear, the outside diameters of the gear anc ly thesame.

Signed at Chicago, county of Cook and State of Illinois, this 26 day of March 1931.

ARNOLD LACK.

ciated with each cr'ankpin. a part of eachcounterbalance Weight being located in thatothrbearing surfaces being substantial- V 

